21st Century L-Arginine 1000mg Tablet

21st Century L-Arginine 1000mg Tablet is a single-ingredient amino acid dietary supplement from 21st Century, a US supplement brand. Each tablet provides 1000mg of L-arginine, and it is supplied as oral tablets in a pack of 30. Please refer to the product label for the full list of inactive ingredients, such as binders and fillers used to form the tablet.

L-arginine is a conditionally essential amino acid. Healthy adults normally make enough of it, and it is also present in everyday protein foods such as meat, poultry, fish, eggs, dairy, nuts, seeds and legumes. In the body, L-arginine is used to build proteins, takes part in the urea cycle that helps clear nitrogen, and serves as a starting material for creatine and several signalling molecules.

This tablet may be used as a dietary supplement by adults who want an additional source of L-arginine on top of their usual diet. Because a single tablet already contains a full gram of L-arginine, it is important to stay within the label dose and to avoid doubling up with other arginine-containing products such as sports drinks or amino acid blends. L-arginine can lower blood pressure and interacts with nitrates, PDE5 inhibitors and blood pressure medicines, so adults on these medicines, or with a history of heart attack, should check with a doctor or pharmacist before use.

Swallow the tablet whole with a full glass of water; do not crush or chew it. The product information suggests taking it preferably on an empty stomach, although taking it with a light meal may help if you experience stomach discomfort. Always follow the directions printed on the product label or the advice of your doctor or pharmacist.

Adults: the product information indicates 1 tablet once or twice daily, or as directed by a healthcare professional. Please confirm the recommended dose on the product label, as label directions take priority.

Do not exceed the recommended daily intake. This product is not intended for children or adolescents. If you miss a dose, take the next one at the usual time rather than taking two at once.

Refer to the expiry date printed on the product packaging. Do not use the tablets after the expiry date has passed.

Store in a cool, dry place, away from direct sunlight, heat and moisture. Keep the container tightly closed after each use and keep it out of reach of children. Follow any additional storage instructions printed on the product label.

• Common: stomach discomfort, bloating, nausea or abdominal cramps, which are more likely at higher intakes.
• Common: diarrhoea or loose stools, especially when the product is taken in larger amounts.
• Common: headache or mild flushing in some people.
• Less common: dizziness or light-headedness related to a drop in blood pressure, particularly when combined with blood pressure medicines.
• Serious: allergic reactions such as rash, itching, swelling of the face, lips or throat, or difficulty breathing; worsening of asthma symptoms has also been reported with L-arginine. Stop use and seek urgent medical attention.

• People who have had a recent heart attack: L-arginine is not recommended after a heart attack, as a clinical study in this group raised safety concerns.
• People taking nitrates for angina or chest pain, unless specifically approved by their doctor.
• People with low blood pressure, or those prone to dizziness or fainting.
• People with a history of herpes infections (including cold sores), as L-arginine may support herpes virus activity in laboratory studies.
• People with known allergy or hypersensitivity to L-arginine or any other ingredient in the product.
• People with guanidinoacetate methyltransferase (GAMT) deficiency, an inherited disorder of creatine metabolism.

• Nitrates (e.g. glyceryl trinitrate, isosorbide mononitrate or dinitrate, used for angina): L-arginine may add to the blood-pressure-lowering effect of nitrates and increase the risk of dizziness or fainting. Do not combine without your doctor’s advice.
• PDE5 inhibitors (e.g. sildenafil, tadalafil): taking L-arginine together with a PDE5 inhibitor may cause an additive drop in blood pressure. Speak to your doctor or pharmacist before combining them.
• Blood pressure medicines (e.g. ACE inhibitors, angiotensin receptor blockers, calcium channel blockers, beta blockers, diuretics): there may be an additive blood-pressure-lowering effect, so your blood pressure may need closer monitoring.
• ACE inhibitors, angiotensin receptor blockers and potassium-sparing diuretics (e.g. spironolactone): L-arginine may raise blood potassium levels, particularly in people with reduced kidney function.
• Diabetes medicines: L-arginine may influence blood sugar levels, so people taking glucose-lowering medicines should monitor their readings and speak to their doctor.
• Other L-arginine sources (sports drinks, pre-workout powders, amino acid blends or multi-ingredient men’s formulas): check labels to avoid taking more L-arginine in total than intended.

• Remember that one tablet already provides 1000mg of L-arginine; there is no need to add other arginine products.
• If the tablet upsets your stomach, try taking it with a light snack and mention it to your pharmacist.
• Rise slowly from sitting or lying down if you notice light-headedness, and seek advice if it persists.
• Bring the bottle to your doctor’s appointments so your full medicine list, including supplements, is known.
• Stop taking it at least two weeks before any planned surgery and inform your surgeon.
• Store the tablets in their original, tightly closed container away from heat and moisture.

Precautions: This product is intended for adults. There is not enough reliable information on the safety of supplemental L-arginine during pregnancy or breastfeeding, so do not use it during these times unless your doctor advises it. Use with caution if you have kidney disease, liver disease, diabetes, asthma or allergies, or if you are taking any blood pressure, heart or diabetes medicines. Stop taking the product at least two weeks before planned surgery, as it may affect blood pressure. Avoid taking several products containing L-arginine at the same time.

When to See a Doctor or Pharmacist: Speak to a doctor or pharmacist before use if you have heart disease, a history of heart attack, low or high blood pressure, kidney problems or recurrent herpes infections, or if you take nitrates, PDE5 inhibitors such as sildenafil or tadalafil, or blood pressure medicines. Stop using the product and seek medical attention promptly if you develop chest pain, fainting, severe dizziness, a rash, swelling of the face or lips, or difficulty breathing.